1. Field of the Invention
The present invention relates to a method for supporting metal nanoparticles and particularly to a method for fixing metal nanoparticles stabilized by a protective coating.
2. Background Art
Known methods for producing metal fine particles and obtaining nano-size (1 to 1,000 nm) metal particles (metal nanoparticles) include wet processes that includes producing metal particles in a solution with the aid of a chemical reaction, and dry processes that includes depositing metal nanoparticles directly on a substrate with the aid of vacuum technology. For example, Japanese Patent Application Laid-Open (JP-A) No. 2007-231306 and International Publication No. 2006/132308 disclose methods including depositing atoms or molecules constituting a nanoparticle precursor on an ionic liquid, which is a salt consisting of a cation(s) and an anion(s) and in a liquid state at room temperature, in which metal nanoparticles are produced by sputtering using a system and a procedure similar to those of chemical vapor deposition (CVD) or physical vapor deposition (PVD). More specifically, it is disclosed that the process includes placing a target and an ionic liquid in a vacuum chamber, applying an electric power to the target to perform sputtering to the ionic liquid, so that nanoparticles are produced on or in the ionic liquid.